1. Technical Field
Embodiments of the present disclosure relate to semiconductor memory technology, and more particularly, to a data storage device including a non-volatile memory device and a method of driving the same.
2. Related Art
Recently, as demands for portable digital application devices, such as digital cameras, MP3 players, personal digital assistants (PDAs), smart phones, and the like, increase, the non-volatile memory device market is growing rapidly. Examples of non-volatile memory devices include a read-only memory (ROM), a programmable ROM (PROM), an erasable ROM (EROM), an electrically EPROM (EEPROM), and a flash memory device. From among the non-volatile memory devices, a flash memory device, e.g., a NAND flash memory device is one of the most popular non-volatile memory devices that enables miniaturization and high performance of digital application devices.
In a charge trap type flash memory device among flash memory devices, data is programmed or erased by providing or removing charges in or from a charge trap layer through tunneling or injecting of electrons into the charge trap layer in a memory cell. If charges stored in a programmed memory cell are gradually lost as time elapses, the programmed memory cell may be determined as an erased cell in which no data is stored when a threshold voltage of the programmed cell decreases to be less than a predetermined value. As a result, a data read failure may occur. Therefore, to secure reliability of the charge trap type flash memory device, it is required to achieve excellent data retention capability for maintaining data stored in the programmed cell without applying additional bias to the programmed memory cell.
Recently, as higher integration and larger capacity of non-volatile memory devices are strongly demanded, memory cells are continuously scaled down, and a demand for multi-level memory devices is also increasing. For such scaling down of memory cells and implementation of the multi-level memory device, it is necessary to reduce deterioration of data retention characteristics which is caused by change in a threshold voltage of a memory cell due to spreading of charges trapped in a charge trap layer of the memory cell toward memory cells adjacent to the memory cell. Furthermore, if trapped charges are thermally excited by rise of a temperature caused when a non-volatile memory device operates, the spreading of the trapped charges may be accelerated. Therefore, it is necessary to secure durability of the trapped charges against the thermal excitation.